Probe up to 10 x402 endpoints in parallel and get each one's reachability and decoded price — for an agent comparing several sellers at once. Send {urls:[…]}; returns [{url, reachable, isX402, price?, priceUsd?, error?}]. Each URL is SSRF-validated independently and NO payment is ever sent; one unreachable URL never fails the batch (it is reported per-URL). Reuses the same decoder as x402-probe.